A lichen is a fungus and alga in close symbiotic relationship – so close, in fact, that this can only be seen under a microscope. Lichens can withstand very severe drying out but also need moisture to thrive. It is estimated that there are over 1,000 species of lichen. Lichens and mosses provide testimony to low levels of air pollution, especially by sulphur.
The bigger and more leafy the lichen, the more sensitive it is to air pollution, and fine displays of foliose lichens can be seen decorating trees in woodland along the western seaboard, the trees often festooned with lichens and mosses to the extent that the tree limbs appear furry. A woodland of trees with lichens and mosses has a primeval appearance. Lichen species are also found commonly growing on the soil surface of lawns, especially lawns on poor soil.
Another primitive class of plants is liverwort, known as hepatophyta, which means liverwort in Latin, wort being an old English word for a plant. Under natural conditions, this tiny plant is similar to moss, but produces flat, lobed structures, leaflike and generally flat on the site surface. These are very common on the compost surface of plants raised in commercial nurseries for sale in garden centres. Although considered unsightly, these liverworts are much too small to be competitive with even small garden plants.
Although most plants lie low and grow very little in winter, the cooler and wetter part of the year suits lichens and mosses very well. These ancient life forms are well adapted for cooler conditions and they need a continuous supply of water. In summer, when the sun is hotter, the lichens and mosses dry up and wait until rain falls.
Growth of mosses and lichens
When autumn comes and the leaves fall from trees, the best period of the year for mosses, lichens and liverworts begins. Winter offers a much more reliable supply of rainwater and the light is better when the tree leaves have fallen. Between autumn and early summer, lichens and mosses luxuriate, especially during mild weather. While they like dampness and better access to light, cold weather slows their development.
In many gardens, especially in rainy localities, lichens and mosses often grow on ornamental trees and fruit trees. This does no harm to the host tree, which just provides a site on which to live. But some people are convinced that the lichens will cause damage. It sometimes happens that a weak shrub with reduced leaf cover develops lots of lichen and moss. These grow because the sunlight falls through the branches more readily.
It might appear that the shrub is in decline because of the growth of mosses and lichens but this is not the case. However, when the cover of mosses and lichens gets really heavy, this will reduce the amount of light reaching the shrub leaves on lower branches, and to that extent will reduce growth. There is no reason to remove lichens and mosses from trees or shrubs, usually some light feeding, or a dressing of good garden compost, can be given to encourage the shrub or tree to recover.
The veg garden
The next few weeks offer an opportunity to make preparations for the coming year’s activities in the vegetable garden. At this time of year, vegetable gardens fall into two camps – those well prepared for the coming year and those with which nothing has been done since last September.
The ground can be dug over now or left to dry out to become suitable for cultivating with a small rotovator. In any case, try to have everything ready to take the first opportunity to get in some early vegetables if the ground conditions are right.
Some crops such as garlic, shallots and early beans and peas can go in as early as February and early potatoes can be put in too in the milder parts. Buy vegetable seeds to be ready and try out some new kinds.
Botanical info
There are hundreds of different types of moss species.
They are classed as bryophytes, a very ancient order of
plants that evolved long before flowering plants. They are defined by their lack of veins for the transport of water within.
They are small plants that need free moisture for reproduction, so it is not surprising for them to proliferate in damp areas and regions of high rainfall. The best-known moss is the sphagnum that grows on raised bogs and is used to make peat-based compost. The use of moss peat for this purpose is controversial.
Trees, shrubs & roses
If a young tree has been knocked sideways, but is not quite out of the ground, it is sometimes possible to straighten it by pulling it back into position and anchoring it with three steel wires or cables. Dig out the soil to allow the lifted roots to be re-planted.
Flowers
If the ground is not too wet, border flowers can be lifted and divided, if necessary. Many of these are beginning to show signs of waking up. Bedding flowers can be started off in a heated propagator now, but it is still too early for most of the easy kinds.
Fruit, vegetables and herbs
Seed potatoes of early varieties can be put in to sprout now. Check on fruit trees to see if they have been rocked by winds. Most dwarfing rootstocks have small roots and the stakes will need to be solid. Lift rhubarb stools for forcing in a dark, warm place.
Lawn
If the soil is firm enough a first mowing can be carried out at any opportunity. If the lawn area is drained, see if the drainage outlets are clear to facilitate the removal of surplus water. Have the mower overhauled or serviced.
Greenhouse and house plants
If they are given reasonable care, Christmas houseplants, such as poinsettia, azalea and cyclamen can be made to last longer. They will need watering but only just enough to keep them moist, certainly do not leave them standing in water. No feeding is needed.
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